1. Field of the Invention
The invention generally relates to an internal combustion engine having variable displacement. Specifically, the invention relates to an internal combustion engine having at least one core piston and at least one piston sleeve per core piston mounted within a cylinder to provide dynamic variable displacement.
2. Background of the Invention
Internal combustion engines used in cars, trucks, boats, and other motor vehicles are required to produce a wide range of power outputs. For example, when a car is accelerating, more power is required than when the car is cruising at a constant speed on the highway. When the car is cruising at constant speed, coasting, decelerating, idling, or starting up, much less power is needed. In conventional engines, additional unnecessary combustion is taking place at these times.
Engines have been developed to take advantage of this. For example, when an eight cylinder engine reaches cruising speed on the highway, and is no longer accelerating, the power needed to maintain the vehicle at that speed, on a flat, level road, is very small. So small, in fact, that the speed of the vehicle can be maintained with less than all of the cylinders firing. In an eight cylinder engine, all eight cylinders would be firing when the vehicle is undergoing high acceleration, such as when the vehicle is running up to speed at it enters a highway on-ramp, or when passing another vehicle on a two lane road. When the vehicle is cruising at constant speed on a level road, coasting, decelerating, idling, or starting up, only two or four of the cylinders would be necessary. The other four or six cylinders are shut down to conserve fuel. Likewise, when that vehicle encounters an incline in the roadway, more of the cylinders can be activated in order to maintain the vehicle's speed.
These engines require complicated controls to detect the driving conditions and to determine when and if cylinders within the engine should be shut down or activated.
Other engines use numerous valves or variable flow valves to increase or decrease the flow of air and fuel into the cylinders. In this type of engine, all of the cylinders are running all the time, but a computer determines how much power the engine needs to output, and adjusts the amount of fuel and air that are supplied to the cylinders accordingly. Thus, when the vehicle is accelerating, the flow or air and fuel to the cylinders would be increased, and when the vehicle is cruising at constant speed on a level roadway, the valves can be adjusted to reduce the amount of fuel and air flowing to the cylinders, or some of the valves may be shut off completely. This can cause problems because intermittent use of the valves can cause them to get “sticky”, and not work properly.
Therefore, there is a need for a variable displacement engine that does not require cylinders to be shut down, and does not involve intermittent use of the valves.